Businesses are being warned about firms offering to renew data protection registrations for exorbitant fees.
Trading standards officers fear groups are cashing in on ignorance of the Data Protection Act.
Firms across Brighton and Hove have received letters from various organisations offering to renew registrations for up to £120.
These notices use threatening language and are on "official-looking" headed notepaper.
Trading standards are telling business owners to apply directly to the Government's Information Commissioner (IC), who charges £35 to maintain a register of data controllers who work at firms.
The registrations - for firms handling personal information - last for three years.
The commissioner, Richard Thomas, said there had been a sharp increase in the number of businesses targeted by bogus data protection "agencies" in the last few weeks.
His organisation has taken more than 60,000 call from across the UK in the past 18 months.
Mr Thomas said: "There is a very real cost in time and effort to businesses anxious to establish whether the communications are official."
Oliver Sweeting, who works for Hove-based recruitment consultancy Commercial Finance People, received a letter asking for £95.
He said: "We'd started the ball rolling with the commissioner and I noticed the addresses were different.
"We double-checked we'd paid the £35 registration fee and contacted trading standards."
Jo Player, of Brighton and Hove trading standards, said taking action was a "very slow and laborious" process.
She said: "Prevention is the key. The commissioner's web site explains everything you need to know and gives a list of companies to avoid."
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